Orifice Plates for Stormwater & Sewer Systems

Fernco Orifice Plates are precision-machined flow control devices designed to regulate and restrict discharge rates within stormwater and sewer systems. Manufactured in the UK to site-specific requirements, each plate is engineered to match the project’s hydrostatic conditions, ensuring accurate and consistent performance.

Available in durable 30mm PE500 HMWPE or 6mm marine grade 1.4401 (316) stainless steel, Fernco Orifice Plates are built to withstand corrosion, chemical effluents and demanding environmental conditions. Suitable for installation into chambers — including round chambers with curved back options — every unit is supplied complete with a mounting kit for straightforward, reliable installation.

Designed in accordance with BS EN 5167-2:2022, Fernco Orifice Plates provide dependable, long-term flow control for infrastructure projects where performance and durability are critical.

  • Manufactured to site-specific requirements

  • Precise control and regulation of fluid flow rates

  • Available in HMWPE or marine grade 1.4401 (316) stainless steel

  • Resistant to corrosion, chemical effluents and extreme temperatures

  • UK-machined for accurate flow performance to BS EN 5167-2:2022

  • Curved back option for installation into round chambers

  • Simple, quick installation with minimal maintenance

    +44 (0) 1226 340 222

    sales@fernco.co.uk

    An orifice plate is an engineered device installed within a pipe system to restrict and regulate fluid flow to a defined rate. Fernco manufactures high quality orifice plates in the UK using either 30mm HDPE or 6mm grade 316 stainless steel, covering standard sizes from DN100 to DN600.

    Each orifice plate is designed to deliver accurate and consistent flow control in stormwater and sewer applications. With excellent durability, corrosion resistance, and chemical stability Fernco orifice plates are engineered for long term performance even in aggressive or demanding conditions.

    Every Fernco orifice plate is custom cut to the project’s exact technical requirements, whether based on site specifications, drawings, or required flow rates. The machined orifice is calculated to match the system’s hydrostatic conditions, ensuring optimal flow regulation. Orifice plates are supplied complete with a mounting kit, comprising of an EPDM sponge seal, resin anchor capsules, and 316 stainless steel studding, enabling straightforward installation into all concrete chambers.

    For round chambers Fernco uses 6mm stainless steel orifice plates or a HDPE orifice plate with a curved back adapter. A HMWPE (HDPE grade PE500) material is used for increased impact strength, UV stability, and durability, when compared to the industry standard HDPE grade PE300.

    Precision Flow Performance

    • Custom-machined orifice calculated to match site hydrostatic conditions

    • Designed for accurate and consistent flow regulation

    • Manufactured in accordance with BS EN 5167-2:2022

    • Available for pipe sizes DN100–DN600

    • Engineered to project-specific requirements

    Robust & Corrosion-Resistant Materials

    • Manufactured in 30mm PE500 HMWPE or 6mm 316 stainless steel

    • Resistant to corrosion, chemical effluents and extreme temperatures

    • PE500 offers higher impact strength than standard PE300

    • UV-stable material for long-term durability

    • Designed for demanding stormwater and sewer environments

    Ready to Install

    • Supplied with EPDM seal, resin capsules and 316 stainless studding

    • Designed for installation into concrete chambers

    • Optional curved back configuration for round chambers

    • 80mm drilled depth with M8 fixings and 4Nm torque

    • Clear installation guidance with temperature-based cure times

    Product CodePipe Internal DiameterA (mm)B (mm)C (mm)Max Weight (kg)Mounting Set
    OP100100mm200200201OPMS-01
    OP150150mm250250201OPMS-01
    OP200200mm300300202OPMS-02
    OP250250mm350350203OPMS-02
    OP300300mm450450306OPMS-03
    OP350350mm500500308OPMS-03
    OP400400mm550550309OPMS-03
    OP450450mm6506503013OPMS-03
    OP500500mm7007003015OPMS-03
    OP600600mm8008003019OPMS-03

    Stainless Steel & Curved Back stainless steel options are available upon request.

    All Orifice Plates are designed and manufactured to site requirements.

    Installation for Concrete Structures

    1. Offer the Orifice Plate to the wall in the desired fixing position, ensuring the opening of the plate is level with the invert level of the pipe.
    2. Mark the drill positions where the wall mounting holes are present and use a spirit level to make sure the Orifice Plate is level.
    3. Remove the Orifice Plate and drill holes where marked using a suitable drill. Use a 10mm drill bit to drill holes to a depth of 80mm for the chemical capsules and bolts to be inserted into.
    4. Clean debris away from the drilled holes and wall surface.
    5. Insert the chemical capsules into the hole.
    6. Using a suitable drill, drill the bolts provided into the holes and chemical capsules, until the depth of the hole has been reached.
    7. Detach the drill from the bolt and remove excess residue from around the hole. Leave the chemical to cure, curing time is indicated in the table below.
    8. Apply sealing tape to the back of the Orifice Plate (see diagram below). If installing two layers of sealing tape, ensure the second layer overlaps any joints in the first layer.
    9. Offer the Orifice Plate over the bolts, tighten on the supplied washers and nuts to the recommended torque of 4Nm.

    Wall Mounting Kit Installation Requirements

    Bolt SizeDrill Bit RequiredDrilled DepthRecommended Tightening Torque
    M810mm80mm4Nm

    Mounting Sets

    Orifice DN All ModelsProduct CodeMounting Set BoltsResin CapsulesEPDM Sealing Strip (m)
    DN100OPMS-01442.5
    DN150
    DN200OPMS-0266
    DN250
    DN300OPMS-03885
    DN350
    DN400
    DN450
    DN500
    DN600

    *All orifice plates come with the mounting kit as standard. Additional Mounting kits can be supplied as per the above table.

    Resin Capsule Cure Time

    Temp °C-15 – -10-9 – -5-4 – 0+1 – +5+6 – +10+11 – +20+21– +30+31 – +40
    Cure Time30 h16 h10 h45 min30 min20 min5 min3 min

    Browse the gallery below to see Fernco’s HDPE Penstocks installed across a range of applications, including chamber and headwall configurations. These images highlight the construction, mounting detail and installed position of each unit, helping you visualise how the penstock integrates within real-world drainage and water management systems.

    Looking for dimensional data, material options or installation details? Download the Orifice Plates data sheet below for complete technical information and specification support.

    Click the button below and complete the short form to download the Orifice Plates data sheet, giving you instant access to the technical information required for accurate specification, design and installation.

    Need the full technical specification?

    The complete product guide for engineers and installers.

    Our datasheet includes everything you need to specify, install or assess Fernco Orifice Plates — from dimensional data and material options to mounting details and installation guidance. It’s a practical reference for engineers, contractors and consultants working across stormwater and sewer infrastructure.

    To access the download, simply complete the short form provided. It only takes a moment and gives you instant access to the full PDF, ready to view, save or share whenever required.

    Frequently Asked Questions

    An orifice plate is an engineered flow-control device installed within a pipe or chamber to restrict and regulate fluid flow to a defined rate. It is commonly used in stormwater and wastewater/sewer systems to ensure consistent, predictable discharge.

    Fernco manufactures orifice plates from durable HMWPE (HDPE grade PE500) or marine-grade 316 stainless steel (1.4401). These materials offer long-term resistance to corrosion, chemical exposure, and extreme temperatures.

    Standard manufacturing covers DN100 to DN600, with all plates custom-cut to match the project’s hydraulic requirements, drawings, or specified flow rates. Larger sizes are available on request in either HMWPE or stainless steel.

    Yes. For round chambers, Fernco supplies either curved 6mm stainless steel plates, or HMWPE plates with a curved-back adapter. This ensures a secure and accurate fit regardless of chamber geometry.

    Yes, all plates are machined in the UK and designed to deliver accurate flow performance in accordance with BS EN 5167-2:2022.

    Each orifice plate is supplied with a complete mounting kit, including:

    • EPDM sponge seal
    • Resin anchor chemical capsules
    • 316 stainless steel studding, washers, and nuts

    Installation is simple and can be completed using standard tools. The process involves drilling anchor holes, inserting chemical capsules, fixing the stud bolts, applying sealing tape, and tightening the plate to the recommended 4Nm torque. Minimal maintenance is required once installed.

    Absolutely, every orifice plate is engineered to the exact hydraulic conditions of the project. The machined orifice size is calculated to deliver precise and reliable flow regulation based on site-specific water levels and flow rates.

    Yes, Fernco’s technical department can calculate the orifice diameter from the desired flow conditions. All orifice plates are supplied with a drawing for approval prior to manufacture.

    Got a question or need help choosing the right product for your project?

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